JP2016050653A - Mechanical seal for submerged pump - Google Patents

Abstract

PROBLEM TO BE SOLVED: To properly seal between a pump chamber and an oil chamber by forming and keeping a lubricant film between sealed end faces in a stable state.SOLUTION: A mechanical seal includes a metallic stationary-side holding ring 12 held on a partitioning wall 3, a ceramics stationary seal ring 13 fitted and fixed to the stationary-side holding ring 12 through O-rings 18, 19 in a non-contact state, a metallic rotary-side holding ring 14 fixed to an impeller shaft 6, a ceramics rotary seal ring 15 fitted and fixed to the rotary-side holding ring 14 through O-rings 23, 24 in a non-contact state, and a spring member for pressing and energizing the stationary seal ring 13 to the rotary seal ring 15, to seal a pump chamber 1 in an outer peripheral-side region and an oil chamber 5 in an inner peripheral-side region of a relative rotary slide-contact part S of both seal rings 13, 15. Inner diameters of both seal rings 13, 15 are the same as each other, and inner peripheral faces of their tip parts 13b, 15b are formed into taper faces 13g, 15g of which diameters are gradually decreased from inner peripheral edges of sealed end faces 13a, 15a.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a mechanical seal for a submersible pump for sealing between a pump chamber and an oil chamber of a submersible pump.

  In the submersible pump, as disclosed in FIG. 1 of Patent Document 1, an oil chamber is formed between the pump chamber and the motor chamber, and the pump chamber and the oil chamber are sealed with a mechanical seal. Yes. Thus, as such a mechanical seal, for example, as disclosed in FIG. 2 of Patent Document 1, a stationary seal ring provided in a partition partitioning the pump chamber and the oil chamber, and penetrating the partition from the motor chamber to the pump chamber An end face contact type configured to shield and seal between the pump chamber and the oil chamber by the relative rotational sliding contact action of the sealing end face which is the end face facing the rotary sealing ring provided on the impeller shaft extending to the well is well known. It is.

  Such an end-face contact type mechanical seal is composed of a material for the sealing ring, one of the two sealing rings is made of a hard material such as ceramics such as SiC or cemented carbide, and the other is made of a soft material such as carbon. It is roughly divided into one (hereinafter referred to as “hard material / soft material seal”) and one in which both sealing rings are composed of the hard materials described above (hereinafter referred to as “hard material / hard material seal”). In this case, slurry fluid containing solid components such as muddy water is often handled. Therefore, when a hard / soft seal is used, the sealing end surface is easily worn and damaged by the slurry, and there is a problem in durability. The sealing function cannot be exhibited over a long period of time. Therefore, in rotating equipment that often handles slurry liquid such as submersible pumps such as submersible pumps, generally hard / soft seals are not used, and both seal rings are made of ceramics and cemented carbides that have excellent wear resistance. A hard material / hard material seal made of a hard material is used.

JP-A-8-334098 JP 2014-1758 A No. 1-221251

  However, since hard materials such as ceramics and cemented carbides do not have self-lubricating properties such as carbon and have a high coefficient of friction, the hard material / hard material seals must be sealed against each other. Heat generation and wear due to sliding contact with the ring are severe, and a good sealing function cannot be exhibited over a long period of time. Also, a lubricating oil film is formed between the sealed end faces by the oil stored in the oil chamber. However, since hard materials such as ceramics are poor in lipophilicity, a stable lubricating oil film is formed and maintained between the sealed end faces. Heat generation due to sliding contact with the other seal ring cannot be suppressed to a great extent. And, due to such heat generation, the oil temperature in the oil chamber rises and the viscosity of the oil decreases, so that the lubricating oil film is not formed on the entire sealed end face, so that the so-called semi-dry state of running out of oil results in the wear of the sealed end face and the sealed end face There is a risk of leakage from the gap. Furthermore, there is a possibility that oil decomposition products due to high temperature accumulate between the sealed end faces, thereby increasing leakage. Such a problem is even more pronounced when liquid paraffin with poor lubricity must be used as oil to be sealed in the oil chamber for food hygiene and environmental pollution, or when the oil chamber is small and the amount of stored oil is small. Will occur.

  By the way, in the hard material / hard material seal, since hard materials such as ceramics have to be processed in a simple shape, the sealing ring is connected to a metal holding ring, and the holding ring is fixed to the partition wall or the impeller shaft. Or devised to hold. Thus, shrink fitting is generally employed as a means for connecting the sealing ring to the holding ring, and as described in paragraph [0028] of Patent Document 2 or FIG. The ring is fitted and integrated into the recess formed in the retaining ring by shrink fitting.

  However, when the seal ring is integrated with the retaining ring by shrink fitting, the compressive stress acting on the outer periphery of the seal ring causes strain over time on the sealed end surface, the two sealed end surfaces do not contact properly, and the relative rotation of the sealed end surfaces There is a possibility that the sealing function due to the sliding contact action is lowered.

  The present invention has been made in view of such a point, and even when both sealing rings are made of a hard material, the above-described problem does not occur, and an appropriate lubricating oil film is stable between the sealing end faces. It can be formed and maintained by, and heat generation and wear due to sliding contact with the other sealing ring can be suppressed as much as possible, and the pump chamber and the oil chamber can be well sealed over a long period of time. An object of the present invention is to provide a mechanical seal for a submersible pump.

  The present invention provides a mechanical seal for a submersible pump loaded between a partition wall that partitions a pump chamber and an oil chamber, and an impeller shaft that extends through the partition wall and extends from the motor chamber to the pump chamber. In order to achieve the object, in particular, a stationary stationary retaining ring made of metal held axially movable on the partition wall via an O-ring, and a stationary sealing ring made of hard material fixed to the stationary retaining ring, A metal rotating side retaining ring fixed to the impeller shaft, a hard rotating ring made of hard material fixed to the rotating side retaining ring, and a spring member that urges the stationary sealing ring to press and contact the rotating sealing ring. The seal chamber seals the pump chamber which is the outer peripheral side region of the relative rotational sliding contact portion and the oil chamber which is the inner peripheral side region thereof by the relative rotational sliding contact action of the sealing end surfaces which are the front end surfaces of both sealing rings. Constructed to be static sealed In the state where the base end portion of the base plate is formed in the recess formed at the distal end portion of the stationary side holding ring, the O-ring is interposed between the opposed peripheral surfaces of the stationary sealing ring and the stationary side holding ring in the recessed portion and between the opposed end surfaces, respectively. The base end portion of the rotary seal ring is fitted and fixed, and the concave portion formed at the tip of the rotary side holding ring is located between the opposing peripheral surfaces of the rotary seal ring and the rotary side holding ring in the concave portion, and the opposite end surface. They are fitted and fixed with an O-ring interposed between them, and the inner diameters of the sealing end surfaces of both sealing rings are made the same, and the inner peripheral surface of the tip portion of each sealing ring is separated from the inner peripheral edge of the sealing end surface. It is proposed to form a tapered surface that gradually decreases in diameter toward the proximal end of the sealing ring.

  In a preferred embodiment of the mechanical seal for such a submersible pump, a balance type mechanical device in which the balance diameter D0 is set to satisfy D1 ≦ D0 ≦ D2 with respect to the inner and outer diameters D1 and D2 of the relative rotational sliding contact portion. It is comprised by the seal | sticker and both sealing rings are comprised by the ceramics or the cemented carbide. In addition, both the sealing rings are configured so that the cross section has a symmetrical shape with respect to the relative rotational sliding contact portion, and the inner and outer diameters of the sealing end surfaces of both sealing rings coincide with the inner and outer diameters of the relative rotational sliding contact portion. It is preferable.

  In the submersible pump mechanical seal of the present invention, since the inner peripheral surface of the tip portion of both seal rings is formed in a tapered surface that gradually decreases in the opposite direction, the oil in the oil chamber is impeller shaft by centrifugal force. The oil flows from the outer peripheral surface of the rotary seal ring to the relative rotational sliding contact portion along the taper surface of the rotary sealing ring, and the oil is reversed at the relative rotational sliding contact portion to the outer peripheral surface of the impeller shaft along the tapered surface of the stationary sealing ring. The oil is forcibly circulated on the inner peripheral side of the relative rotational sliding contact portion. By such oil circulation, the relative rotational sliding contact portion is continuously lubricated and cooled, and a stable lubricating oil film is formed and maintained between the sealed end surfaces, and heat is generated by sliding contact with the mating sealed end surface. Suppressed as much as possible.

  In the submersible pump mechanical seal of the present invention, each sealing ring is fitted and fixed to the recess of the holding ring via an O-ring. Thus, there is no distortion over time on the sealed end face as in the case of connecting to the holding ring by shrink fitting, and both the sealed end faces can be kept in proper contact. Further, when excessive axial thrust acts on the sealing ring, or when the sealing ring and the holding ring are made of different materials having different thermal expansion coefficients, a difference in thermal deformation (difference in thermal expansion or Even when a difference in heat shrinkage occurs, the load acting on the sealing ring can be absorbed and alleviated by the cushioning action caused by the elastic deformation of the O-ring interposed between the sealing ring and the sealing end face. There is no distortion.

  Therefore, according to the mechanical seal for submersible pumps of the present invention, a satisfactory sealing function can be exhibited over a long period of time without causing the problems described at the beginning.

FIG. 1 is a sectional view showing an example of a mechanical seal for a submersible pump according to the present invention. FIG. 2 is an enlarged detailed view showing the main part of FIG. FIG. 3 is a cross-sectional view of the main part corresponding to FIG. 2 showing a modification of the mechanical seal for the submersible pump according to the present invention. FIG. 4 is a cross-sectional view of the main part corresponding to FIG. 2 showing another modification of the mechanical seal for a submersible pump according to the present invention. FIG. 5 is a cross-sectional view of the main part corresponding to FIG. 2 showing still another modification of the mechanical seal for submersible pump according to the present invention. FIG. 6 is a schematic sectional view showing a general configuration of the submersible pump.

  Hereinafter, embodiments for carrying out the present invention will be specifically described with reference to the drawings.

  FIG. 6 is a schematic cross-sectional view of the general configuration of the submersible pump. In general, the submersible pump is arranged between the pump chamber 1 and the motor chamber 2 between the pump chamber 1 and the motor chamber 2, as shown in FIG. An oil chamber 5 is formed which is partitioned by partition walls 3 and 4, respectively, and between the impeller shaft 6 extending from the motor chamber 1 to the pump chamber 2 through the partition walls 3 and 4 and the partition walls 3 and 4, respectively. Mechanical seals 7 and 8 are provided. The motor chamber 2 is provided with a motor 9 for rotationally driving the impeller shaft 6 and a bearing (not shown) of the impeller shaft 6. The impeller 10 attached to the impeller shaft 6 is disposed in the pump chamber 1. Are arranged and a suction port 1a and a discharge port 1b are formed.

  FIG. 1 is a sectional view showing an example of a mechanical seal for a submersible pump according to the present invention, and FIG. 2 is a detailed view showing an enlarged main part of FIG. As shown in FIGS. 1 and 2, the mechanical seal 7 that seals between the two is configured as follows according to the present invention. In the following description, “upper and lower” means the upper and lower sides in FIGS.

  That is, as shown in FIG. 1, the submersible pump mechanical seal 7 according to the present invention is loaded between the partition wall 3 that partitions the pump chamber 1 and the oil chamber 5 and the impeller shaft 6 that passes through the partition wall 3. 3 is fixed to the impeller shaft 6, a stationary stationary ring 12 made of metal that is held by an O-ring 11 so as to be movable in the axial direction, a stationary stationary ring 13 made of a hard material fixed to the stationary side retaining ring 12, and the impeller shaft 6. The metal rotation side holding ring 14 made of metal, the hard sealing ring 15 made of a hard material fixed to the rotation side holding ring 14, and the spring that urges the stationary sealing ring 13 to press and contact the rotation sealing ring 15. And a pump chamber 1 which is an outer peripheral side region of the relative rotational sliding contact portion S by the relative rotational sliding contact action of the sealing end surfaces 13a and 15a which are the front end surfaces of both sealing rings 13 and 15, and the inner periphery thereof. Shield seal against oil chamber 5 which is side area A hard material / hard material seal end face contact type which is configured to so that. In this example, the fluid (sealed fluid) in the pump chamber 1 is slurry liquid such as muddy water, and the oil chamber 5 is not pressurized and oil is stored. The relative rotational sliding contact portion S of the sealed end surfaces 13a and 15a is a portion where both sealed end surfaces 13a and 15a are in contact with each other as shown in FIG. 2, and its inner diameter D1 is the inner diameter of both sealed end surfaces 13a and 15a. The outer diameter D2 is the smaller of the outer diameters of the sealed end faces 13a and 15a.

  As shown in FIG. 1, the partition wall 3 has a plate-like shape in which a through hole of the impeller shaft 6 is formed. The through hole portion formed in the pump chamber side portion (lower portion) 3a in the thickness direction is the oil chamber side portion. (Upper part) The diameter is larger than the through-hole part formed in 3b.

  As shown in FIG. 1, the stationary-side holding ring 12 includes a cylindrical main body 12a, an annular flange 12b protruding outward from the outer peripheral surface of the tip (the outer peripheral surface of the lower end), and the main body 12a from the outer periphery. A rotating body formed of a cylindrical holding portion 12c protruding in the reverse direction (downward) is integrally formed of a metal material such as stainless steel. In this example, the stationary side holding ring 12 is made of stainless steel.

  Thus, as shown in FIG. 1, the stationary side holding ring 12 is fitted and held with its main body part 12a movably in the axial direction (vertical direction) via the O-ring 11 to the pump chamber side part 3a of the partition wall 3. As a result, the partition wall 3 is held so as to be movable in the axial direction while being sealed (secondary seal) with the O-ring 11 therebetween. As shown in FIG. 1, the O-ring 11 is formed on the inner peripheral portion of the through hole portion of the pump chamber side portion 3a of the partition wall 3 while being in pressure contact with the outer peripheral surface of the main body portion 12a of the stationary side holding ring 12. 3c is engaged and held. The distal end surface (lower end surface) of the main body portion 12a of the stationary side retaining ring 12 and the distal end surface (lower end surface) of the flange portion 12b are flush with each other and orthogonal to the axis as shown in FIGS. It is formed on the receiving surface 12d which is an annular plane. As shown in FIGS. 1 and 2, the inner peripheral surface of the holding portion 12c of the stationary seal ring 12 is formed on a holding surface 12e that is a cylindrical surface parallel to the axis and orthogonal to the receiving surface 12d. As shown in FIG. 1, the stationary side retaining ring 12 has an axis line by engaging a drive pin 17 protruding from its base end surface (upper end surface) with an engagement hole 3d formed in the oil chamber side portion 3b of the partition wall 3. Relative rotation with respect to the partition 3 is prevented while directional movement is allowed within a predetermined range.

  As shown in FIGS. 1 and 2, the stationary sealing ring 13 has a trapezoidal tip end portion 13b having a tip end surface (lower end surface) formed as a sealing end surface 13a that is a smooth annular plane orthogonal to the axis, and a rectangular cross section. It is an annular body having a trapezoidal cross section composed of a base end portion 13 c and is fitted and fixed to a recess 12 f formed at the distal end portion of the stationary holding ring 12 via O rings 18 and 19. That is, a recess 12f surrounded by the receiving surface 12d and the holding surface 12e is formed at the tip of the stationary holding ring 12, and the stationary sealing ring 13 is opposed to both the rings 12 and 13 in the recess 12f. The O-ring 18 is clamped between the end surfaces, that is, the base end surface 13d of the stationary sealing ring 13 and the receiving surface 12d of the stationary holding ring 12, and between the opposed peripheral surfaces of both rings 12, 13 in the recess 12f, that is, stationary. The O-ring 19 is clamped between the outer peripheral surface 13e of the sealing ring 13 and the holding surface 12e of the stationary holding ring 12, and is fitted and fixed to the recess 12f in a non-contact state. The O-ring 18 is engaged and held in an O-ring groove formed on the receiving surface 12d of the stationary side retaining ring 12 while being pressed against the proximal end surface 13d of the stationary sealing ring 13, and the O-ring 19 is retained on the stationary side. The O-ring groove formed on the holding surface 12e of the ring 12 is engaged and held in a state of being pressed against the outer peripheral surface 13e of the stationary sealing ring 13.

  By the way, the stationary seal ring 13 is fitted and fixed to the stationary side retaining ring 12 by being press-fitted into the recess 12f of the stationary side retaining ring 12 with the O-rings 18 and 19 interposed therebetween. , 13 is blocked by the frictional engagement force with the O-rings 18, 19, but in this example, in order to more reliably prevent the relative rotation of both rings 12, 13, as shown in FIG. The drive pin 20 protruding from the receiving surface 12d of the side holding ring 12 is engaged with an engagement recess 13f formed in the main body 13b of the stationary seal ring 13.

  As shown in FIG. 2, the inner peripheral surface 13g of the distal end portion 13b of the stationary seal ring 13 has a tapered surface (截) that gradually decreases in diameter from the inner peripheral edge of the seal end surface 13a toward the base end direction (upward direction) of the seal ring 13. Head conical surface). The inclination angle of the tapered surface 13g with respect to the sealed end surface 13a is appropriately set in the range of 15 ° to 75 °. The stationary seal ring 13 is made of a hard material such as ceramics or cemented carbide, and in this example is made of ceramics (for example, silicon carbide sintered material).

  As shown in FIG. 1, the rotation-side holding ring 14 is disposed on the impeller 10 side (lower side) from the stationary sealing ring 13, and from the cylindrical main body portion 14 a and the distal end surface outer peripheral portion (upper end surface outer peripheral portion). From an annular holding portion 14b protruding in the stationary sealing ring direction (upward direction) and an annular fixing portion 14c protruding in parallel with the holding portion 14b from the inner peripheral portion (upper end inner peripheral portion) of the front end surface of the main body portion 14b. Is formed integrally with a metal material (stainless steel in this example) such as stainless steel, and the main body portion 14a has an O-ring 21 interposed between the fixed portion 14c and the impeller shaft 6. By tightening the screwed set screw 22 to the impeller shaft 6, the set screw 22 is fitted and fixed to the impeller shaft 6. The front end surface (upper end surface) of the main body portion 14a of the rotation-side holding ring 14 is configured as a receiving surface 14d orthogonal to the axis, and the inner peripheral surface of the holding portion 14b is held in parallel to the axial line and orthogonal to the receiving surface 14d. As shown in FIG. 2, the front end portion of the rotation side holding ring 14 is surrounded by the receiving surface 14d, the holding surface 14e, and the outer peripheral surface of the fixing portion 14c parallel to the holding surface 14e. An annular recess 14f is formed. In addition, the protrusion amount from the main-body part 14a of the holding | maintenance part 14b and the fixing | fixed part 14c is made the same or substantially the same.

  As shown in FIGS. 1 and 2, the rotary seal ring 15 has a trapezoidal tip end portion 15b having a tip end surface (upper end surface) formed as a sealed end surface 15a which is a smooth annular plane orthogonal to the axis, and a rectangular cross section. It is an annular body having a trapezoidal cross section composed of a base end portion 15 c, and is fitted and fixed to a concave portion 14 f formed at the distal end portion of the rotation-side holding ring 14 via O-rings 23 and 24. That is, the rotary seal ring 15 is formed between the opposed end surfaces of the rings 14 and 15 in the concave portion 14 f, that is, between the base end surface (lower end surface) 15 d of the rotary seal ring 15 and the receiving surface 14 d of the rotary side holding ring 14. The ring 23 is clamped and the O-ring 24 is sandwiched between the opposed peripheral surfaces of the rings 14 and 15 in the recess 14 f, that is, between the outer peripheral surface 15 e of the rotary seal ring 15 and the holding surface 14 e of the rotary side holding ring 14. In a pressed state, it is fitted and fixed to the recess 14f in a non-contact state. The O-ring 23 is engaged and held in an O-ring groove formed on the receiving surface 14d of the rotation-side holding ring 14 while being in pressure contact with the base end surface 15d of the rotation sealing ring 15, and the O-ring 24 is held on the rotation-side holding ring. The O ring groove formed on the holding surface 14e of the ring 14 is engaged and held in a state of being pressed against the outer peripheral surface 15e of the rotary sealing ring 15.

  By the way, the rotary seal ring 15 is fitted and fixed to the rotary side holding ring 14 by press-fitting the rotary side holding ring 14 with the O-rings 23 and 24 interposed in the recess 14f of the rotary side holding ring 14. , 15 is prevented by the frictional engagement force with the O-rings 23, 24. In this example, in order to more reliably prevent the relative rotation of the two rings 14, 15, as shown in FIGS. As described above, the drive pin 25 protruding from the receiving surface 14 d of the rotation side holding ring 14 is engaged with the engagement recess 15 f formed in the main body portion 15 b of the rotation sealing ring 15.

  As shown in FIG. 2, the inner peripheral surface 15g of the distal end portion 15b of the rotary seal ring 15 has a tapered surface (截) that gradually decreases in diameter from the inner peripheral edge of the seal end surface 15a toward the base end direction (downward) of the seal ring 15. Head conical surface). The inclination angle of the tapered surface 15g with respect to the sealing end surface 15a is preferably set to 15 ° to 75 °, and is appropriately set within this range. The rotary seal ring 15 is made of a hard material such as ceramics or cemented carbide. In this example, the rotary seal ring 15 is made of the same ceramic as the stationary seal ring 13. In addition, the distal end surface (upper end surface) of the inner peripheral side portion (fixed portion 14c) of the rotation side holding ring 14 with respect to the rotation sealing ring 15 is the base end (taper surface) of the taper surface 15g of the rotation sealing ring 15 in the axial direction. 15g and the boundary portion between the inner peripheral surface of the base end portion 15c of the rotary sealing ring 15) or the position closer to the sealing end surface 15a than the base end. In this example, as shown in FIG. 2, the base end of the fixing portion 14c is located at a position corresponding to a substantially intermediate position of the tapered surface 15g in the axial direction.

  In this example, as shown in FIG. 2, both seal rings 13 and 15 have a cross-sectional shape symmetrical with respect to the relative rotational sliding contact portion S (vertical symmetry), that is, a common member having the same shape and the same material. The inner and outer diameters of the sealing end faces 13a and 15a of both the sealing rings 13 and 15 are equal to the inner and outer diameters D1 and D2 of the relative rotational sliding contact portion S.

  As shown in FIG. 1, the spring member 16 is composed of a plurality of coil springs loaded at equal intervals in the circumferential direction between the main body portion 12 a of the stationary side retaining ring 12 and the oil chamber side portion 3 b of the partition wall 3. The stationary seal ring 13 is urged in the axial direction so as to press and contact the rotary seal ring 15 via the stationary holding ring 12.

  Further, the diameter of the contact surface of the O-ring 11 in the stationary side retaining ring 12 (the outer peripheral surface of the main body portion 12a of the stationary side retaining ring 12), that is, the balance diameter D0 is the relative rotation of the sealed end surfaces 13a and 15a as shown in FIG. The inner and outer diameters D1 and D2 of the sliding contact portion S are set to satisfy D1 ≦ D0 ≦ D2 (optimally D0 = (D1 + D2) / 2). That is, the mechanical seal 7 is set so that the balance ratio κ is 1 or less, and the fluid in the pump chamber 5 (slurry as a fluid to be sealed) is placed on the stationary sealing ring 13 (that is, the stationary holding ring 12 that fixes the stationary sealing ring 13). It is configured as a balanced mechanical seal in which axial thrust due to the pressure of liquid (back pressure) does not act as much as possible. As the second mechanical seal 8 that seals the motor chamber 2 and the oil chamber 5, a well-known mechanical seal (for example, a mechanical seal disclosed in Patent Documents 1 to 3) is used. Omitted.

  In the submersible pump mechanical seal 7 according to the present invention configured as described above, the inner peripheral surfaces of the tip end portions 13b and 15b of both the sealing rings 13 and 15 are reverse from the inner peripheral edges of the sealed end surfaces 13a and 15a. Since the tapered surfaces (conical frusto-conical surfaces) 13g and 15g gradually reduce in diameter, the oil in the oil chamber 5 is actively guided to the relative rotational sliding contact portion S of the sealed end surfaces 13a and 15a and is relatively It will circulate and flow around the rotating sliding contact portion S, and both the sealing rings 13 and 15 are made of a hard material that does not have self-lubricating properties such as ceramics or cemented carbide and has a high friction coefficient. Even in the case of the material / hard material seal, the relative rotation sliding contact portion S can be continuously lubricated and cooled effectively, and a good sealing function (mechanical sealing function) is exhibited.

  That is, since the viscosity of the oil is high, the oil forms a layer together with the rotating members 6, 14, 15 in the portions where the rotating members (the impeller shaft 6, the rotating side holding ring 14, and the rotating seal ring 15) contact with the oil. It can be rotated. This is a so-called oil layer rotation phenomenon. Then, a centrifugal force acts on the oil layer around the rotating members 6, 14, and 15 with the rotation, and the centrifugal force gradually increases in the outer circumferential direction.

  Accordingly, in the inner peripheral side region of the relative rotational sliding contact portion S, as indicated by an arrow P in FIG. 2, the oil is a portion on the inner peripheral side from the rotary seal ring 15 in the rotary holding ring 14 from the impeller shaft 6 by centrifugal force. It flows outward on the surface of (fixing part 14c). Further, as indicated by an arrow Q in FIG. 2, the oil flows on the tapered surface 15 g of the rotary sealing ring 15 to the inner diameter portion of the sealing end surface 15 a of the sealing ring 15, that is, the inner diameter portion of the relative rotational sliding contact portion S due to centrifugal force. The part S is lubricated.

  The inner diameters of both sealed end faces 13a and 15a are the same, and the inner peripheral surfaces of the tip portions 13b and 15b of both sealed rings 13 and 15 are tapered surfaces 13g inclined in the opposite direction from the inner peripheral edges of the sealed end faces 13a and 15a, Therefore, the oil that has reached the inner diameter portion of the relative rotational sliding contact portion S on the rotating tapered surface 15g is reversed at the inner diameter portion as shown by an arrow R in FIG. It is extruded to the taper surface 13g. Since the tapered surface 13g is stationary and centrifugal force is not acting, the oil is continuously pushed out from the inner diameter portion to the tapered surface 13g, so that the oil is shown by an arrow T in FIG. Then, it is caused to flow in the direction of the outer peripheral surface of the impeller shaft 6 along the tapered surface 13g.

  In this way, on the inner peripheral side of both the sealing rings 13 and 15, a circulating oil flow as shown by arrows Q, R and T in FIG. 2 is generated along the tapered surfaces 13g and 15g. Lubrication and cooling of the sealing end faces 13a and 15a, that is, the relative rotational sliding contact portion S are continued and effectively performed. .

  Therefore, the lubricating oil film is stably formed and maintained in the relative rotational sliding contact portion S, and the heat generation due to the contact (sliding contact) of the sealed end faces 13a and 15a is suppressed as much as possible. Good sealing function.

  Further, since the stationary seal ring 13 and the rotary seal ring 15 are fitted and fixed to the stationary side holding ring 12 and the rotation side holding ring 14 through O-rings 18, 19 and 23, 24 in a non-contact state, the sealing ring As in the case where the ring is fixed to the retaining ring by shrink fitting, compressive stress does not act on the outer peripheral portions of the sealing rings 13 and 15, so that distortion with time does not occur in the sealing rings 13 and 15 or the sealing end faces 13 a and 15 a. In addition, the sealing rings 13 and 15 and the holding rings 12 and 14 are made of different materials having different thermal expansion coefficients. However, a difference in thermal deformation (heat) between the sealing rings 13 and 15 and the holding rings 12 and 14 is obtained. Even under temperature conditions where a difference in expansion amount or a difference in heat shrinkage occurs, the difference in thermal deformation amount is absorbed by the O-rings 19 and 24, and distortion occurs in the sealing rings 13 and 15 or the sealing end faces 13a and 15a. There is nothing. Further, when an excessive axial compressive force acts on the seal rings 13 and 15, that is, when the axial thrust for pressing the stationary seal ring 13 against the rotary seal ring 15 becomes higher than necessary, the O-rings 18 and 23 The axial compression force is absorbed and relaxed by elastic deformation. Further, the mechanical seal 7 configured as described above is configured as a balanced mechanical seal in which the balance diameter D0 is D1 ≦ D0 ≦ D2 with respect to the inner and outer diameters D1 and D2 of the relative rotational sliding contact portion S and the balance ratio κ is 1 or less. Therefore, the contact pressure of the stationary seal ring 13 to the rotary seal ring 16 is not applied by the pressure (back pressure) of the pump chamber 1. Therefore, even when the pressure in the pump chamber 1 is high, the contact pressure of the sealed end faces 13a and 15a does not become excessive, and heat generation and wear due to the contact of the sealed end faces 13a and 15a are suppressed as much as possible.

  For these reasons, according to the mechanical seal 7 for a submersible pump according to the present invention, heat generation, wear, and distortion of the sealed end faces 13a and 15a are prevented as much as possible, and the pump chamber 1 is excellent over a long period of time. Can be sealed.

  In addition, the structure of the mechanical seal for submersible pumps according to the present invention is not limited to the above-described embodiment, and can be appropriately improved and changed without departing from the basic principle of the present invention.

  For example, as shown in FIG. 3, the distal end surface of the inner peripheral side (fixed portion 14 c) of the rotation-side holding ring 14 with respect to the rotation sealing ring 15 is the base end of the tapered surface 15 g of the rotation sealing ring 15 in the axial direction ( The taper surface 15g and the inner peripheral surface of the base end portion 15c of the rotary seal ring 15 can be located at the same position or substantially the same position. In this case, similar to the case shown in FIG. 2, a circulating oil flow as shown by arrows P, Q, R, and T in FIG. 3 is generated. Further, as shown in FIG. 4, the rotation-side holding ring 14 can be configured to have no fixed portion 14c. In this case, the oil flows from the outer peripheral surface of the impeller shaft 6 to the tapered surface 15g of the rotary seal ring 15 as indicated by an arrow U in FIG. 4, and thereafter, as indicated by arrows Q, R, and T in FIG. 2 and a circulating flow similar to the case shown in FIG. 2 is generated on the inner peripheral side of the relative rotational sliding contact portion S. In order for the oil flow indicated by the arrow U to be performed effectively, as shown in FIG. 4, the inner peripheral surface of the base end portion 15 c of the rotary seal ring 15 is made as close as possible to the outer peripheral surface of the impeller shaft 6. It is preferable to keep it. Further, the O-ring 11 that seals between the partition wall 3 and the stationary side retaining ring 12 is engaged and retained in an O-ring groove 13h formed on the outer periphery of the main body 12a of the stationary side retaining ring 12, as shown in FIG. You may make it make it. In this case, as shown in FIG. 5, the balance diameter D0 is the diameter of the surface with which the outer peripheral surface of the O-ring 11 contacts in the partition wall 3, and similarly to the above, D1 ≦ D0 ≦ D2 (optimally D0 = (D1 + D2) / 2). 3 to 5 have the same structure as the mechanical seal 7 shown in FIG. 1 and FIG. 2 except for the above points, the same parts are shown in FIG. 3 to FIG. The same reference numerals as those shown in FIG. 1 and FIG.

DESCRIPTION OF SYMBOLS 1 Pump chamber 2 Motor chamber 3 Partition 3a Pump chamber side part 3b Oil chamber side part 3c O ring groove 3d Engagement hole 4 Partition 5 Oil chamber 6 Impeller shaft 7 Mechanical seal (mechanical seal for underwater pump)
DESCRIPTION OF SYMBOLS 8 Mechanical seal 9 Motor 10 Impeller 11 O-ring 12 Static side holding ring 12a Main body part 12b Eaves part 12c Holding part 12d Receiving surface 12e Holding surface 12f Recessed part 13 Static sealing ring 13a Sealing end surface 13b Tip part 13c Base end part 13d Base end face 13e Outer peripheral surface 13f Engaging recess 13g Tapered surface 13h O-ring groove 14 Rotating side retaining ring 14a Body portion 14b Holding portion 14c Fixing portion 14d Receiving surface 14e Holding surface 14f Recessed portion 15 Rotating sealing ring 15a Sealing end surface 15b Tip portion 15c Base end portion 15d Base end surface 15e Outer peripheral surface 15f Engaging recess 15g Tapered surface 16 Spring member 17 Drive pin 18 O-ring 19 O-ring 20 Drive pin 21 O-ring 22 Set screw 23 O-ring 24 O-ring 25 Drive pin 0 Balance D1 outside diameter S relative rotational sliding contact area of the inner diameter D2 relative rotational sliding contact portion of the relative rotational sliding contact portion

Claims (4)

In a mechanical seal for a submersible pump loaded between a partition wall that partitions the pump chamber and the oil chamber and an impeller shaft that passes through the partition wall and extends from the motor chamber to the pump chamber through the oil chamber,
A stationary stationary ring made of metal held in the partition wall through an O-ring so as to be movable in the axial direction, a stationary stationary ring made of a hard material fixed to the stationary side retaining ring, and made of metal fixed to the impeller shaft A rotating member holding ring, a rotating seal ring made of a hard material fixed to the rotating side retaining ring, and a spring member for urging the stationary sealing ring to press contact with the rotating sealing ring. It is configured to shield and seal the pump chamber which is the outer peripheral side region of the relative rotational sliding contact portion and the oil chamber which is the inner peripheral side region thereof by the relative rotational sliding contact action of the sealing end surface which is the front end surface of the ring,
The base end portion of the stationary seal ring has an O-ring interposed between the opposed peripheral surfaces of the stationary seal ring and the stationary side holding ring and the opposed end surfaces in the recess formed in the distal end of the stationary holding ring. It is fitted and fixed in the
The base end portion of the rotary seal ring has an O-ring interposed between the opposed peripheral surfaces of the rotary seal ring and the rotary side holding ring and the opposed end surfaces in the concave portion formed at the distal end portion of the rotary side holding ring. It is fitted and fixed in the
The inner diameters of the sealing end faces of both sealing rings are made the same, and the inner peripheral surface of the distal end portion of each sealing ring is formed into a tapered surface that gradually decreases in diameter from the inner peripheral edge of the sealing end face toward the proximal end of the sealing ring. A mechanical seal for submersible pumps.   The balance type mechanical seal is configured such that the balance diameter D0 is set to satisfy D1 ≦ D0 ≦ D2 with respect to the inner and outer diameters D1, D2 of the relative rotational sliding contact portion. Mechanical seal for submersible pumps to be described.   The mechanical seal for a submersible pump according to claim 1 or 2, wherein both seal rings are made of ceramics or cemented carbide. Both seal rings are configured so that the cross-section is symmetrical with respect to the relative rotational sliding contact portion, and the inner and outer diameters of the sealing end surfaces of both sealing rings coincide with the inner and outer diameters of the relative rotational sliding contact portion. The mechanical seal for submersible pumps according to any one of claims 1 to 3, wherein the mechanical seal is used.

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